U.S. patent number 7,281,919 [Application Number 11/101,139] was granted by the patent office on 2007-10-16 for system for controlling a volume of material on a mold.
This patent grant is currently assigned to Molecular Imprints, Inc.. Invention is credited to Pankaj B. Lad, Ian M. McMackin, Steven C. Shackleton, Van N. Truskett.
United States Patent |
7,281,919 |
Shackleton , et al. |
October 16, 2007 |
**Please see images for:
( Certificate of Correction ) ** |
System for controlling a volume of material on a mold
Abstract
A system for controlling a volume of liquid on a mold that
features a body defining a volume with an aperture formed into the
body and positioned proximate to the mold. A pump system is in
fluid communication with the body, and the aperture and the pump
system are established to create a stream of fluid moving between
the mold and the volume. In this manner a quantity of fluid is
removed while retained upon the mold is a desired portion of the
fluid to undertake imprint lithographic processes.
Inventors: |
Shackleton; Steven C. (Austin,
TX), McMackin; Ian M. (Austin, TX), Lad; Pankaj B.
(Austin, TX), Truskett; Van N. (Austin, TX) |
Assignee: |
Molecular Imprints, Inc.
(Austin, TX)
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Family
ID: |
36578467 |
Appl.
No.: |
11/101,139 |
Filed: |
April 7, 2005 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20060121141 A1 |
Jun 8, 2006 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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11101140 |
Apr 7, 2005 |
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11006363 |
Dec 7, 2004 |
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11005742 |
Dec 7, 2004 |
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Current U.S.
Class: |
425/216;
425/215 |
Current CPC
Class: |
B82Y
40/00 (20130101); B82Y 10/00 (20130101); G03F
7/0002 (20130101); Y10S 977/887 (20130101) |
Current International
Class: |
B29C
31/00 (20060101) |
Field of
Search: |
;425/215-218,810 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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02-24848 |
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Jan 1990 |
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JP |
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02-92603 |
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Apr 1990 |
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JP |
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WO 98/24070 |
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Jun 1998 |
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WO |
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Other References
Abstract of Japanese Patent 02-92603, Aug. 12, 2004. cited by other
.
Abstract of Japanese Patent 02-24848, Jan. 26, 1990. cited by other
.
Chou et al., Nanoimprint Lithography, Journal of Vacuum Science
Technolgoy B 14(16), pp. 4129-4133 Nov. 1, 1996. cited by other
.
U.S. Appl. No. 10/858,566, naming Inventors Truskett et al.,
entitled A Method for Dispensing a Fluid on a Substrate, filed Jun.
1, 2004. cited by other .
U.S. Appl. No. 11/005,742, naming Inventors McMackin et al.,
entitled Method for Fast Filling of Templates for Imprint
Lithography using on Template Dispense, filed Dec. 7, 2004. cited
by other .
U.S. Appl. No. 11/006,363, naming Inventors McMackin et al.,
entitled System for Controlling a Volume of Material Remaining on a
Mold Employed in Fast Filling Imprint Lithography Processes, filed
Dec. 7, 2004. cited by other .
U.S. Appl. No. 11/012,375, naming Inventors Xu et al., entitled
Method to Reduce Adhesion between a Conformable Region and a Mold,
filed Dec. 15, 2004. cited by other .
Nerac.com Retro Search, Fluid Dispensing, May 4, 2005. cited by
other .
U.S. Appl. No. 11/143,092, naming Inventors Lad et al., entitled
Fluid Dispensing and Drop-on-Demand Dispensing for Nano-Scale
Manufacturing, filed Jun. 2, 2005. cited by other .
Brubaker et al., Investigating The Use of Spray-Coating Technology
in MEMS Applications, Micro Magazine, pp. 45-55 Mar. 1, 2004. cited
by other .
U.S. Appl. No. 11/459,797, naming Inventors Choi et al., entitled
Method for Providing Desirable Wetting and Release Characteristics
between a Mold and a Polymerizable Composition, filed Jul. 25,
2006. cited by other.
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Primary Examiner: Mackey; James P.
Assistant Examiner: Bodawala; Dimple N.
Attorney, Agent or Firm: Carter; Michael D. Fish &
Richardson P.C.
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATIONS
The present application is a continuation-in-part of U.S. patent
application Ser. No. 11/006,363, filed Dec. 7, 2004 now abandoned,
entitled SYSTEM FOR CONTROLLING A VOLUME OF MATERIAL REMAINING ON A
MOLD EMPLOYED IN FAST FILLING IMPRINT LITHOGRAPHY PROCESSES, and
having Steven C. Shackleton, Ian M. McMackin, Pankaj B. Lad and Van
N. Truskett listed as inventors; a continuation-in-part of U.S.
patent application Ser. No. 11/005,742, filed Dec. 7, 2004 now
abandoned, entitled METHOD FOR FAST FILLING OF TEMPLATES FOR
IMPRINT LITHOGRAPHY USING ON TEMPLATE DISPENSE and having Ian M.
McMackin, Pankaj B. Lad and Van N. Truskett listed as inventors;
and a divisional of U.S. patent application Ser. No. 11/101,140
filed Apr. 7, 2005, filed herewith, entitled METHOD FOR FAST
FILLING OF TEMPLATES FOR IMPRINT LITHOGRAPHY USING ON TEMPLATE
DISPENSE, and having Ian M. McMackin, Pankaj B. Lad and Van N.
Truskett listed as inventors. All of the aforementioned patent
applications are incorporated by reference herein.
Claims
What is claimed is:
1. A system for controlling a volume of liquid on a mold, said
system comprising: a body defining a void with an aperture formed
into said body and positioned proximate to said mold, with an air
bearing being disposed on opposed sides of said aperture, defining
a pair of spaced-apart air bearings; and a pump system in fluid
communication with said body, with said aperture and said pump
system being established to create a stream of fluid moving between
said mold and said void to remove a quantity of said fluid while
maintaining a portion of said fluid upon said mold.
2. The system as recited in claim 1 wherein said body further
includes an island extending from a surface of said body, with said
aperture being disposed in said island so that said aperture is
disposed between said mold and said surface.
3. The system as recited in claim 1 wherein said body further
includes a recess formed into a surface of said body, with said
aperture being disposed within said recess.
4. The system as recited in claim 1 wherein said pump system
generates a vacuum in said void.
5. The system as recited in claim 1 wherein said pump system
generates a positive pressure in said void.
6. The system as recited in claim 1 further including disposing an
air bearing on opposed sides of said aperture, defining a pair of
spaced-apart air bearings, with each of said pair of spaced-apart
air bearings including an air bearing element comprising a
plurality of volumes each of which has differing pressure
levels.
7. The system as recited in claim 1 further including disposing a
plurality of air bearing elements on opposing sides of said
aperture, each of which includes a plurality of volumes a pair of
which are in fluid communication with said pump system to provide
one of the volumes of said pair with a positive pressure, with the
remaining volume of said pair having a vacuum and separated
therefrom by an additional volume held at an ambient pressure.
8. The system as recited in claim 1 wherein said aperture has a
length associated therewith sufficient to extend between opposed
sides of said mold.
9. A system for controlling a volume of liquid on a mold, said
system comprising: a body defining a void with an aperture formed
into said body and positioned proximate to said mold to place said
void in fluid communication with said mold, with an air bearing
being disposed at each end of said aperture, defining a pair of
spaced-apart air bearings; and a pump system in fluid communication
with said aperture and said pair of spaced-apart air bearings, with
said aperture and said pump system being established to create a
stream of fluid moving between said mold and said void to remove a
quantity of said fluid while maintaining a portion of said fluid
upon said mold and each of said pair of spaced-apart air bearings
including an air bearing element comprising a plurality of volumes
having dimensions established to be maintained at differing
pressure levels.
10. The system as recited in claim 9 wherein said body further
includes an island extending from a surface of said body, with said
aperture being disposed in said island so that said aperture is
disposed between said mold and said surface.
11. The system as recited in claim 9 wherein said body further
includes a recess formed into a surface of said body, with said
aperture being disposed within said recess.
12. The system as recited in claim 9 wherein said pump system
generates a vacuum in said void.
13. The system as recited in claim 9 wherein said pump system
generates a positive pressure in said void.
14. A system for controlling a volume of liquid on a mold, said
system comprising: a body defining a void with an aperture formed
into said body and positioned proximate to said mold to place said
void in fluid communication with an ambient, with an air bearing
being disposed at each end of said aperture, defining a pair of
spaced-apart air bearings each of which includes an air bearing
element comprising a plurality of recessed areas of a surface
separated by lands.
15. The system as recited in claim 14 wherein said air bearing
element further includes said first, second recessed areas, with
said second recessed area substantially surrounding said first
recessed area, with a said first recessed area defining a volume
greater than a volume of said second recessed area.
16. The system as recited in claim 14 wherein said air bearing
element further includes said first, second and third recessed
areas, with said second recessed area substantially surrounding
said first recessed area, and said third recessed area
substantially surrounding said first and second recessed areas,
with said third recessed area defining a volume greater than a
volume of said second recessed area and less than a volume of said
first recessed area.
17. The system as recited in claim 16 wherein said first recessed
area have a rectangular shape, defining a rectangular perimeter,
with said second and third recessed areas having a shaping
conforming to said perimeter.
18. The system as recited in claim 15 wherein each of said pair air
bearings includes a plurality of air bearing elements.
19. The system as recited in claim 15 wherein each of said pair of
air bearing are integrally formed with said body.
20. A system for controlling a volume of liquid on a mold, said
system comprising: a body defining a void with an aperture formed
into said body and positioned proximate to said mold, said body
further including an island extending from a surface of said body,
with said aperture being disposed in said island so that said
apertures is disposed between said mold and said surface; and a
pump system in fluid communication with said body, with said
aperture and said pump system being established to create a stream
of fluid moving between said mold and said void to remove a
quantity of said fluid while maintaining a portion of said fluid
upon said mold.
21. A system for controlling a volume of liquid on a mold, said
system comprising: a body defining a void with an aperture formed
into said body and positioned proximate to said mold, with an air
bearing on opposed sides of said aperture, defining a pair of
spaced-apart air bearings, with each of said pair of spaced-apart
air bearings including an air bearing element comprising a
plurality of volumes each of which has differing pressure levels;
and a pump system in fluid communication with said body, with said
aperture and said pump system being established to create a stream
of fluid moving between said mold and said void to remove a
quantity of said fluid while maintaining a portion of said fluid
upon said mold.
22. A system for controlling a volume of liquid on a mold, said
system comprising: a body defining a void with an aperture formed
into said body and positioned proximate to said mold, with a
plurality of air bearing elements on opposing sides of said
aperture, each of which includes a plurality of volumes a pair of
which are in fluid communication with said pump system to provide
one of the volumes of said pair with a positive pressure, with the
remaining volume of said pair having a vacuum and separated
therefrom by an additional volume held at an ambient pressure; and
a pump system in fluid communication with said body, with said
aperture and said pump system being established to create a stream
of fluid moving between said mold and said void to remove a
quantity of said fluid while maintaining a portion of said fluid
upon said mold.
23. A system for controlling a volume of liquid on a mold, said
system comprising: a body defining a void with an aperture formed
into said body and positioned proximate to said mold, wherein said
aperture has a length associated therewith sufficient to extend
between opposed sides of said mold; and a pump system in fluid
communication with said body, with said aperture and said pump
system being established to create a stream of fluid moving between
said mold and said void to remove a quantity of said fluid while
maintaining a portion of said fluid upon said mold.
Description
BACKGROUND OF THE INVENTION
The field of the invention relates generally to nano-fabrication of
structures. More particularly, the present invention is directed to
a system for filling the features of a template for use in imprint
lithography.
Nano-fabrication involves the fabrication of very small structures,
e.g., having features on the order of nanometers or smaller. One
area in which nano-fabrication has had a sizeable impact is in the
processing of integrated circuits. As the semiconductor processing
industry continues to strive for large production yields while
increasing the circuits per unit area formed on a substrate,
nano-fabrication becomes increasingly important. Nano-fabrication
provides greater process control while allowing increased reduction
of the minimum feature dimension of the structures formed. Other
areas of development in which nano-fabrication have been employed
include biotechnology, optical technology, mechanical systems and
the like.
An exemplary nano-fabrication technique is commonly referred to as
imprint lithography and is described in detail in numerous
publications, such as US published patent application 2004/0065976
filed as U.S. patent application Ser. No. 10/264,960, entitled
"Method and a Mold to Arrange Features on a Substrate to Replicate
Features having Minimal Dimensional Variability"; US published
patent application 2004/0065252 filed as U.S. patent application
Ser. No. 10/264,926, entitled "Method of Forming a Layer on a
Substrate to Facilitate Fabrication of Metrology Standards"; and US
published patent application 2004/0046271 filed as U.S. patent
application Ser. No. 10/235,314, entitled "Method and a Mold to
Arrange Features on a Substrate to Replicate Features having
Minimal Dimensions Variability"; all of which are assigned to the
assignee of the present invention. The fundamental imprint
lithography technique as shown in each of the aforementioned
published patent applications includes formation of a relief
pattern in a polymerizable layer and transferring a pattern
corresponding to the relief pattern into an underlying substrate.
To that end, a template, having a template active area, is employed
spaced-apart from the substrate with a formable liquid present
between the template and the substrate. The liquid is solidified to
form a solidified layer that has a pattern recorded therein that is
conforming to a shape of the surface of the template active area.
The substrate and the solidified layer are then subjected to
processes to transfer, into the substrate, a relief image that
corresponds to the pattern in the solidified layer.
One manner in which to locate the polymerizable liquid between the
template and the substrate is by depositing the liquid on the
substrate. Thereafter, the polymerizable liquid is concurrently
contacted by both the template and the substrate to spread the
polymerizable liquid over the surface of the substrate and fill the
features of the template. It is desirable to minimize the time
required to fill the features of the template, referred to as fill
time. To that end, the polymerizable liquid may be deposited
directly on the template to quickly fill the features thereof.
However, it is desirable to control the quantity of liquid on the
mold. Thus, there is a need to provide improved techniques to fill
the features of a template.
SUMMARY OF THE INVENTION
A system for controlling a volume of liquid remaining on a mold
features a body defining a volume with an aperture formed into the
body and positioned proximate to the mold. A pump system is in
fluid communication with the body, and the aperture and the pump
system are established to create a stream of fluid moving between
the mold and the volume. In this manner a quantity of fluid is
removed while a portion of the fluid upon the mold is retained. In
this manner, the mold may be flooded with imprinting fluid with the
quantity desired to undertake imprint lithography process being
established by removal of the quantity. As a result, the time to
fill the features of the mold is reduced while control over the
portion remaining for imprint lithographic processes is provided.
These and other embodiments are discussed further below.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of a lithographic system in accordance
with the present invention;
FIG. 2 is a simplified elevation view of a lithographic system,
shown in FIG. 1, employed to create a patterned imprinting layer in
accordance with one embodiment of the present invention;
FIG. 3 is a detailed side view showing the fluid dispense mechanism
included in the system, shown in FIG. 1, in accordance with a first
embodiment of the present invention;
FIG. 4 is a detailed side view showing the fluid dispense mechanism
included in the system, shown in FIG. 1, in accordance with a
second embodiment of the present invention;
FIG. 5 is a bottom-up view of a template shown in FIG. 1 having a
mold thereon;
FIG. 6 is a simplified side view of the template shown in FIG. 5,
having liquid polymerizable material disposed thereon, with a
vacuum wipe employed to remove a quantity of the liquid
polymerizable material in accordance with the present
invention;
FIG. 7 is a detailed view of an orifice included in the vacuum wipe
shown in FIG. 6;
FIG. 8. is a detailed bottom-up view of the body of the vacuum wipe
shown in FIG. 6 coupled to a pump system;
FIG. 9 is a detailed plan view of an air bearing element shown in
FIG. 8;
FIG. 10 is a cross-sectional view of the air bearing element shown
in FIG. 9 taken across line 10-10;
FIG. 11 is a simplified plan view showing the body shown in FIG. 6
in superimposition with the template shown in FIG. 5;
FIG. 12 is a simplified plan view showing a vacuum wipe in
accordance with a first alternate embodiment of the present
invention;
FIG. 13 is a simplified plan view showing a vacuum wipe in
accordance with a second alternate embodiment of the present
invention;
FIG. 14 is a cross-sectional view of the template shown in FIG. 5
taken along lines 14-14;
FIG. 15 is a cross-sectional view of a substrate shown in FIG. 1
with a layer of material disposed thereon;
FIG. 16, is a cross-sectional view of the substrate shown in FIG.
15, after patterning thereof with the template shown in FIG. 14, in
accordance with one embodiment of the present invention;
FIG. 17 is a cross-sectional view of the substrate shown in FIG. 15
patterned with the template shown in FIG. 14, in accordance with a
first alternate embodiment of the present invention;
FIG. 18 is a cross-sectional view of the template shown in FIG. 14,
having liquid polymerizable layer disposed thereon in accordance
with one embodiment of the present invention;
FIG. 19 is a cross-sectional view of the substrate shown in FIG. 1,
after patterning thereof with the template shown in FIG. 18 in
accordance with a second alternate embodiment of the present
invention; and
FIG. 20 is a cross-sectional view of the substrate shown in FIG. 15
after patterning thereof with the template shown in FIG. 18, in
accordance with a third alternate embodiment of the present
invention.
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 depicts a lithographic system 10 in accordance with one
embodiment of the present invention that includes a pair of
spaced-apart bridge supports 12 having a bridge 14 and a stage
support 16 extending therebetween. Bridge 14 and stage support 16
are spaced-apart. Coupled to bridge 14 is an imprint head 18, which
extends from bridge 14 toward stage support 16. Disposed upon stage
support 16 to face imprint head 18 is a motion stage 20. Motion
stage 20 is configured to move with respect to stage support 16
along X and Y axes and may provide movement along the Z axis as
well. An exemplary motion stage device is disclosed in U.S. patent
application Ser. No. 10/194,414, filed Jul. 11, 2002, entitled
"Step and Repeat Imprint Lithography Systems," assigned to the
assignee of the present invention and is incorporated by reference
herein. A radiation source 22 is coupled to system 10 to impinge
actinic radiation upon motion stage 20.
Referring to both FIGS. 1 and 2, connected to imprint head 18 is a
template 24 having a mold 26 thereon, which may define a smooth or
planar surface or have a pattern formed therein. As shown, mold 26
includes a pattern having a plurality of features defined by a
plurality of spaced-apart recesses 28 and projections 30.
Projections 30 have a width W.sub.1, and recesses 28 have a width
W.sub.2, both of which are measured in a direction that extends
transversely to the Z axis. The plurality of features defines an
original pattern that forms the basis of a pattern to be
transferred into a substrate 32 positioned on motion stage 20. To
that end, imprint head 18 is adapted to move along the Z axis and
vary a distance "d" between mold 26 and substrate 32.
Alternatively, or in conjunction with imprint head 18, motion stage
20 may move template 24 along the Z-axis. In this manner, the
features on mold 26 may be imprinted into a flowable region
employed to pattern substrate 32, discussed more fully below.
Radiation source 22 is located so that mold 26 is positioned
between radiation source 22 and substrate 32, with actinic
radiation generated by radiation source 22 propagating through mold
26. As a result, it is desired that mold 26 be fabricated from
material that is substantially transparent to the actinic
radiation. Exemplary materials from which mold 26 may be fabricated
include fused-silica, quartz, silicon, organic polymers, siloxane
polymers, borosilicate glass, fluorocarbon polymers, metal, and
combinations of the above dependent upon the actinic radiation
employed. An exemplary system is available under the trade name
IMPRIO 100.TM. from Molecular Imprints, Inc. having a place of
business at 1807-C Braker Lane, Suite 100, Austin, Tex. 78758. The
system description for the IMPRIO 100.TM. is available at
www.molecularimprints.com and is incorporated herein by
reference.
System 10 facilitates formation of a patterned layer 40 upon
substrate 32 that has a shape complementary to a shape of mold 26.
As a result, patterned layer 40 includes projections 46 that are
complementary to the shape of recessions 28 and recesses 48 that
are complementary to the shape of protrusions 30. Patterned layer
40 results from the placement of polymerizable material between
substrate 32 and mold 26 and minimizing distance "d", leaving
projections 46 with a thickness t.sub.1 and recesses 48 with a
thickness t.sub.2. Thickness t.sub.2 is referred to as a residual
thickness. Thicknesses "t.sub.1" and "t.sub.2" may be any thickness
desired, dependent upon the application.
After distance "d" has been reached, radiation source 22 produces
actinic radiation that polymerizes and cross-links the material of
pattern layer 40. This process may be repeated several times to
sequentially pattern different regions (not shown) of substrate 32,
referred to as a step and repeat process. Alternatively mold 26 may
be sized so that the entire area of a surface of substrate 32 is
patterned concurrently, i.e., with one imprinting by mold 26.
In accordance with the present invention, patterned layer is formed
by depositing polymerizable material on mold 26. Specifically, a
measure of the polymerizable material, in a flowable/liquid state,
is deposited upon mold 26. A portion of the measure ingresses into
one or more of recessions 28, filling the volume thereof. A
quantity of the measure of flowable polymerizable material is
present upon regions of the surface of mold 26 proximate to the one
or more recessions 28 of said recess, i.e., outside of the volume
of all of the recessions 28 present. Typically, the portion of the
flowable polymerizable material fills the entire volume of each of
recessions 28 present. Thereafter, substantially all, if not all,
of the quantity of the flowable polymerizable material outside of
the volume of recessions 28 is removed from mold 26. In this
fashion, all or a sub-group of recessions 28 of mold 26 is
completely filled with flowable polymerizable material.
Referring to FIGS. 1 and 3, depositing flowable polymerizable
material may be achieved employing a number of techniques. For
example, system 10 may include one or more fluid dispensing
mechanisms 41 that may include one or more spray nozzles, one of
which is shown as nozzle 42. Nozzle 42 is in fluid communication
with a supply 43, the flowable polymerizable material and a pump
45. Pump 45 provides fluid pressure to facilitate projection of
material 40 from nozzle 42, ensuring a sufficient number of
droplets (not shown) accumulate on mold 26 to essentially flood the
same with a coating 38 of flowable imprinting material to ensure
all features are covered and filled. Nozzle 42 is mounted to motion
stage 20 to facilitate having nozzle 42 to be selectively placed in
superimposition with any portion of mold 26. In this manner,
coating 38 may be deposited on mold 26 in any pattern desired.
Referring to FIGS. 1 and 4, another manner by which to deposit
flowable polymerizable material to mold 26 employs a fluid
dispensing mechanism 141 with a transfer platen 47 containing the
flowable polymerizable material. Platen 47 may be selectively
disposed between mold 26 and substrate 32, or positioned adjacent
to substrate 32, with mold 26 selectively positioned to be in
superimposition therewith. Mold 26 is placed in contact with the
flowable polymerizable material contained in platen 47. The area of
platen 47 is established so that the entire area of mold 26 may be
placed in contact with material 40 contained in platen 47. It is
conceivable that this dip-coating technique may be employed to
create a self-assembled monolayer of flowable polymerizable
material on mold 26 not unlike a Langmiur-Blodgette monolayer.
However, it is sufficient to merely create a contiguous coating 38
that covers and/or fills the features of the pattern of mold
26.
Referring to FIG. 5, removal of the quantity of flowable
polymerizable material outside of the volume of recessions may be
achieved by subjecting the same to a stream of fluid, such as a
gas. To that end, a vacuum wipe technique, an air knife technique
or both may be employed. In both cases, mold 26 is exposed to
stream of fluid 60 that is contiguous between opposed sides 62 and
64 of mold 26, in a first direction, such as X, and is
substantially smaller than mold 26, in a second direction, such as
Y that extends transversely to the first direction. Relative
movement between stream of fluid 60 and mold 26 along the Y
direction occurs, e.g., so that movement from side 66 to side 68
occurs. This exposes the entire area of mold 26 to stream of fluid
60.
Referring to FIGS. 5 and 6, in one embodiment, stream of fluid 60
is produced by a vacuum wipe 70 that includes a body 72 defining a
volume 74 and having an orifice 76 placing said volume in fluid
communication with an ambient 78 in which vacuum wipe 70 is
disposed. Volume 74 is placed in fluid communication with a pump
system 80 over a feed line 82. Pump system 80 creates a pressure
differential between volume 74 and ambient 78 so that volume 74 is
pressurized to a level that is less than the pressure of ambient
78, e.g., pump system 80 may create a negative pressure within
volume 74. The aforementioned pressure differential results in the
quantity of liquid polymerizable material not disposed in
recessions 28 being drawn away from mold 26 and into a reservoir
(not shown) of pump system 80. The pressure differential, however,
is selected so that the portion of liquid polymerizable material
disposed within the volume of recessions 28, remains or a thin
layer of polymerizable material remains covering recessions 28.
This is shown with respect to recessions 128, 228 and 328.
To that end, as shown in FIGS. 7 and 8, orifice 76 is provided with
a substantially rectangular configuration having a length, l,
measured along the X direction between opposed ends 77 and 79, as
well as a width w, and measured along the Y direction. Length, l,
extends in a direction transverse to the relative motion between
body 72 and mold 26, with width, w, being substantially smaller
than the length l. Typically length, l, is at least five times
greater than width, w. In the present example, length, l, is
typically greater than the dimension of mold 26, which is
approximately 25-30 millimeters, and width, w, is selected to
optimize removal of the polymerizable material at approximately
0.49 millimeters. Body 72 is disposed so that orifice 74 faces mold
26 and is spaced-apart therefrom a distance, h, shown more clearly
in FIG. 6. Distance h, is selected based upon several factors,
including the viscosity of the polymerizable material disposed on
mold 26, the adhesions characteristics of the polymerizable
material to mold 26, as well as the pressure differential between
volume 74 and ambient 78.
Referring to FIGS. 6, 8 and 9, to assist in controlling height, h,
body 72 includes two spaced-apart sets of air bearings, shown as 80
and 90, flanking orifice 76. Specifically, orifice 76 extends
between air bearings 80 and 90, with end 77 being positioned
proximate to air bearing 80 and spaced-apart therefrom. End 79 is
positioned proximate to air bearing 90 and spaced-apart therefrom,
e.g., 2 millimeters. Air bearings 80 and 90 are in fluid
communication with a pump system 100 that may be configured to
provide the necessary fluid flow. To that end, each of air bearings
80 and 90 includes a plurality of bearing elements, shown as 81-88
and 91-98. Each of elements 81-88 is positioned in abutting
relationship with each bearing element 81-88 adjacent thereto to
form a sequence of bearing elements collinear in a direction
transverse to the direction along which length, l, is measured. As
shown, the sequence along which bearing elements 81-88 are arranged
is along the Y direction. In a similar fashion, bearing elements
91-98 are arranged on an opposing side of said body 72.
Referring to FIGS. 9, 10 and 11, each of bearing elements 81-88 and
91-98, are typically integrally formed with body 72, and includes a
plurality of coplanar areas 99, 108 and 110 of body 72. As shown,
three polygonal regions are concentrically formed into recessed
areas 102, 104 and 106. Although each of regions 102, 104 and 106
has rectangular shapes, any shape may be employed, including
non-polygonal shapes, such as a circle. Although not required, the
area of region 102 is substantially larger than the area of either
region 104 or region 106, with the region of 106 being greater than
the area of region 104. Region 102 is separated from region 104 by
land 108 that surrounds region 102 and is approximately 1
millimeter in width. An additional land 110 separates region 104
and 106. The apex surfaces of lands 108, 110 and surface 99 lie in
a common plane. A throughway 112 extends from region 104 parallel
to plane P along a direction transverse to terminating in an
aperture (not shown) in said body 72. A throughway 112 is also
present in region 102, placing the same in fluid communication with
pump system 100. Similarly, a throughway 116 is present in region
106, placing the same in fluid communication with pump system
100.
In operation, a pressure differential is created between regions
102, 104 and 106, with region 106 having a greater pressure than
either regions 102 and 104. Typically pump system 100 introduces a
positive flow of fluid into throughway 116 pressurizing region 106
to be greater than ambient pressure. Pump system 100 typically
applies a vacuum to throughway 114, creating a vacuum in region
102. Region 104 is typically maintained at ambient pressure levels
and operates to stabilize the pressure differential present in
regions 102 and 106.
Referring to FIGS. 6 and 11, body 72 is placed in superimposition
with template 24 so that orifice 76 extends across an extent of
mold 26 with air bearings 80 and 90 being in superimposition with
regions of template 24 outside of mold 26. Relative motion between
template 24 and body 72 along a single direction is undertaken,
referred to as a pass, to remove the liquid polymerizable material,
as discussed above. If necessary, however, additional passes may
occur in the same direction as the first pass, or in opposite or
orthogonal directions, by simply re-orientating template 24 and
body 72 by rotating one with respect to the other 90.degree..
As seen, air bearings 80 and 90 are arranged so as to create a
positive flow of fluid to impinge upon template 24 pushing body 72
away therefrom to maintain desired spacing, h. It has been found
beneficial to independently control fluid propagating between pump
system 100 and throughways 114 and 116. In this manner sudden
changes in pressure, such as when one or more of air bearing
elements are no longer in superimposition with template 24, shown
as 81-83 and 91-93, does not vary the pressure associated with
regions 102, 104 and 106 of the remaining air bearing elements,
shown as 84-88 and 94-98, that are still in superimposition with
template 24. In addition to the independent control of fluid flow
to air bearing elements 81-88 and 91-98, improved stability of the
position between mold 26 and orifice 76 may be achieved by
including more air bearing elements in each of air bearings so as
to extend the length of the same in the direction of travel.
Referring to FIG. 12, in alternative embodiment, vacuum wipe 170
may be formed with a body 172 in which orifice 174 is disposed upon
a region 175, spaced apart from mold 26 a distance, h. The
remaining portions of the surface of body 72 facing template 74, is
spaced-apart from template 74 a distance d, which is substantially
greater than distance h. In this manner, region 175 forms an
island.
Referring to FIG. 13, in yet another embodiment, region 275 of body
272 is recessed so as to be spaced apart from mold 26 a distance,
h. Air bearings 80 and 90, however, are spaced-apart from regions
of template 24 outside of mold 26 a distance s, which may be the
same as or less than distance h. In this manner, were mold 26
formed as a mesa 29, as shown, mold 26 could be positioned between
air bearings 80 and 90 so as to be coplanar therewith.
Referring to FIG. 6, in an alternative embodiment, vacuum wipe may
operate as a gas knife. In this manner, pump system 80 creates a
positive pressure in volume 74 to produce a high velocity "sheet"
of gas (not shown) expelled from orifice 76. This gas "sheet"
removes the quantity of fluid not filling the volume of recessions
128, 228 and 328, effectively blowing-off the same. This may be
employed in conjunction with the vacuum wipe so that the sheet of
gas pushes undesired liquid polymerizable material from the mold 26
and vacuum wipe collects the undesired liquid polymerizable
material blown-off by the sheet. Alternating between the gas knife
and the vacuum wipe could occur during a single pass or performed
on successive passes, as desired. Additionally, the positive
pressure in volume 74 may be established so as to function as a
drier of fluid disposed on mold 26, e.g., within recessions 128,
228 and 328. In this fashion, the velocity of the "sheet" of gas
would be established to reduce the probability of removing fluid on
mold 26 while drying the same.
The present deposition techniques provide added flexibility when
patterning substrates. For example, as shown in FIGS. 14-16, mold
26 may be provided with flowable imprinting material deposited so
that only the portions of the same, shown as 200, 202, 204 and 206,
present in recesses 28, remain. The quantity (not shown) of
flowable imprinting material not disposed within recesses 28 are
absent, i.e., removed. As a result, portions 200, 202, 204 and 206,
may be disposed on substrate 32, which may have a pre-existing
layer thereon, shown as 300. Pre-existing layer may be one of
several layers. For example, layer 300 may be flowable
polymerizable material deposited employing any number of deposition
techniques, including spin-coating and drop dispense techniques.
Were layer 300 formed from a material that is polymerized by the
same actinic radiation, e.g., by changes in thermal radiation, and
changes in ultra violet radiation, as portions 200, 202, 204 and
206, it is possible to deposit portions 200, 202, 204 and 206,
before polymerization of the flowable material from which layer 300
is formed. In this manner portions 200, 202, 204 and 206 may be
polymerized concurrently with the material from which layer 300 is
formed so that the material of portions 200, 202, 204 and 206 may
cross-link with the material of layer 300, forming an integral
patterned layer 400. As a result, layer 300 defines residual
thickness t.sub.2, shown in FIG. 2. In other words, the residual
thickness t.sub.2, of patterned layer 40 may be independent of the
fluid dispensed to be imprinted with patterned mold 26.
Alternatively, it is possible to deposit portions 200, 202, 204 and
206 upon a layer after solidification of layer 300. In this manner
portions are polymerized and cross-linked after deposition
thereupon. This requires that the adhesion of the polymerized and
cross-linked material from which portions 200, 202, 204 and 206 are
formed demonstrate adequate preferential adhesion to solidified
layer 300 so that portions 200, 202, 204 and 206 are retained
thereon upon separation of mold 26 therefrom. In the present of the
aforementioned preferential adhesion, additional deposition
techniques may be employed to deposition layer 300, including, but
not limited to, atomic layer deposition, chemical vapor deposition,
physical vapor deposition spin-on and the like. As a result,
patterned layer 400 is formed in which portions 200, 202, 204 and
206 are not integrally formed with layer 300, but are merely
adhered thereto. Additionally, it is possible to completely or
partially cure portions 200, 202, 204 and 206 before depositing the
same on layer 300. This may be achieved, for example, by using the
drier function (not shown) mentioned above. Subsequently, layer 300
is polymerized and cross-linked. It should be noted that the matter
from which layer 300 may be formed includes constituent components
that differ from that which portions 200, 202, 204 and 206 are
formed. For example, layer 300 may be formed from an organic
material and portions 200, 202, 204 and 206 may be formed from an
inorganic material and vice-versa.
Referring to FIGS. 18-20, it should be noted, however, that
benefits may be present when leaving a small portion of a quantity
599 of flowable polymerizable material not present in recesses 28,
i.e., the portion of flowable polymerizable material not included
in portions 600, 602, 604 and 606. In this manner, quantity 599
defines the residual thickness t.sub.2, shown in FIG. 2. The
combination of quantity 599 and portions 600, 602, 604 and 606,
facilitate fabrication of an integral patterned layer, 700, on
substrate 32, with the residual thickness being dependent upon the
presence of flowable polymerizable material deposited on mold 26.
It is not necessary to deposit layer 700 directly on substrate 32.
Rather, substrate may have a pre-existing layer 800 deposited
thereon that may have any of the properties discussed above with
respect to layer 300. In this manner, patterned layer 700 may be
integrally formed with layer 800 (not shown) or may merely be
adhered thereto, shown in FIG. 20 as layer 900.
The embodiments of the present invention described above are
exemplary. Many changes and modifications may be made to the
disclosure recited above, while remaining within the scope of the
invention. Therefore, the scope of the invention should not be
limited by the above description, but instead should be determined
with reference to the appended claims along with their full scope
of equivalents.
* * * * *
References